On October 24, 1993, a Cessna 140 (registration N73003) was involved in an aviation accident near Frankenmuth, MI. Investigators recorded the probable cause as: The pilot's inadvertent activation of the mixture control instead of the carburetor heat, facilitated by the identical design of the control knobs. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
A pilot lost engine power during cruise flight and made an emergency landing in a crop field. Investigation revealed that the mixture and carburetor heat controls were identical, leading to potential misidentification.
What happened
During cruise flight, the aircraft experienced a sudden loss of engine power. The pilot initiated an emergency procedure and landed the airplane in a nearby crop field. Upon inspection, the aircraft was found to be substantially damaged.
The investigation
Post-accident examination of the aircraft revealed that the control knobs for the mixture and carburetor heat were identical in shape, size, and color. This design feature created a high potential for confusion between the two controls.
Findings
The pilot indicated that he may have inadvertently activated the mixture control instead of the carburetor heat. The identical control knobs likely contributed to this error. The loss of engine power was directly attributed to this misidentification.
Probable cause
The pilot's inadvertent activation of the mixture control instead of the carburetor heat, facilitated by the identical design of the control knobs.